<PRE><B>Question 1041593</B>
The meat department in a grocery store purchased 800 lb of hamburger that is 90% lean beef. How many lbs of hamburger that is 75% lean must be mixed with this 90% lean mix to produce hamburger that is 85% lean beef? 
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lean + lean = lean
0.90*800 + 0.75x = 0.85(800+x)
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Multiply thru by 100 to get:
90*800 + 75x = 85*800 + 85x
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10x = 5*800
x = 400 lbs (amt. of 75% lean to add)
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Cheers,
Stan H.
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